High temperature yarn fibrillation method



April 23, 1968 MCINTOSH ET AL 3,379,807

HIGH TEMPERATURE YARN FIBRILLATION METHOD Filed Dec. 14, 1964 INVENTORS E. K. Mc/NTOSH J. R. WILLIAMS MM; (mam ATTORNEY United States Patent 3,379,807 HIGH TEMPERATURE YARN FIBRILLATION METHOD Euell K. McIntosh, Pensacola, Fla, and .Iarnes R. Williams, Rohertsdale, Ala, assignors to Monsanto Company, St. Louis, Mo., a corporation of Delaware Filed Dec. 14, 1964, Ser. No. 418,185 7 Claims. (Cl. 264162) ABSTRACT OF THE DISCLOSURE A method of texturing synthetic thermoplastic yarn by passing it under tension into and out of contact with the periphery of a molten-thermoplastic-wettable, heated roll. The surface of the yarn melts and adheres to the roll when in contact therewith. When the yarn pulls out of contact with the roll, small fibrils are formed on the yarn surface which, upon cooling, solidify to form permanent fibrils.

This invention relates to texturing yarn. More particularly, it pertains to a method for producing fibrils on the surface of synthetic thermoplastic yarn.

Nylon and polyester are among the important synthetic thermoplastics from which yarns can be made.

Nylon is a long-chain synthetic thermoplastic polymeric amide having recurring amide groups as an integral part of the main polymer chain. This polymer is capable of being formed into a filament in which the structural elements are oriented along the filament axis. The term nylon includes nylon-66 (polyhexamethylene adipamide), nylon-6 (polymeric 6-arnino caproic acid), nylon-610 (polyhexamethylene sebacamide), nylon-4, nylon-7, nylon-11, etc., and filament and fiber forming copolymers thereof.

Polyester is a long-chain synthetic thermoplastic polymer of at least 85 percent by weight of an ester of a dihydric alcohol and terephthalic acid.

Synthetic thermoplastic yarns, especially those made from nylon and polyester, have met with enthusiastic commercial acceptance. These yarns are strong, resistant to moisture, and durable. Yet, synthetic thermoplastic yarns also have a few undesirable characteristics: poor hand, poor cover, and excess luster.

An object of this invention is to make synthetic thermoplastic yarn even more attractive.

A more precise object of this invention is to provide a method for decreasing the luster and improving the hand and cover of synthetic thermoplastic yarn.

Other objects will become apparent from the following descriptive material.

The above objects are achieved in the provision of a method for raising fibrils on the surface of synthetic thermoplastic yarn. To raise such fibrils yarn is passed into and out of contact with the periphery of a moltentherrnoplastic-wettable heated roll. The temperature of the periphery of this roll is at least as high as the melt temperature of the yarn, thus melting the yarn surface. As the yarn surface melts, it temporarily adheres to the roll. When the yarn pulls out of contact with the roll, small fibrils are formed on its surface which, upon cooling, solidify to form permanent fibrils.

In the drawing:

FIGURE 1 is a schematic, perspective view of a particular yarn string-up useful in practicing the invention;

FIGURE 2 is an elevational view of the heated roll shown in FIGURE 1 in contact with the tensioned yarn;

FIGURE 3 is an enlarged elevational view of fibrils being formed by yarn contact with the heated roll shown in FIGURES 1 and 2; and

FIGURE 4 is a perspective view of yarn fibrillated in accordance with the method of the invention.

To aid in further describing the invention reference will first be made to FIGURE 1. Yarn it), which can be either monofilarnent or multifilament, is withdrawn from spin cake 12 and passed over snubber guide 14. From snubber guide 14 yarn 10 is advanced at a particular peripheral rate of speed by nip rolls 16. Yarn 10 is stretched by draw roll 20 rotating at a second peripheral rate of speed, such rate being greater than the peripheral speed of nip rolls 16. The point at which stretching takes place is localized by draw pin 18. The yarn is wrapped at least once, but usually three or more times, about draw roll 20 and separator roll 30. As the yarn passes from draw roll 20 to separator roll 30 and back, it contacts the periphery of heated roll 22. Roll 22 is electrically heated, the circuit being represented by electrical leads 26. Heated roll 22 is an idler roll, driven by contact between flange 28 and draw roll 20. Surface 24 of heated roll 22 is heated to a temperature at least as high as the melt temperature of the yarn being fibrillated. Yarn It moves from draw roll 2t) to yarn traverse 32 which distributes the yarn in an orderly manner on bobbin 34.

FIGURE 2 further illustrates the embodiment of the invention shown in FIG. 1. As shown in FIG. 1, yarn 10, wrapped about draw roll 29 and separator roll 30', passes while under tension into and out of contact with heated surface 24. As stated before, heated roll 22 is driven by means of contact between flange 28 and draw roll 20.

FIGURE 3 illustrates the crux of the invention. Yarn 10, here shown as a monofilarnent for purposes of clear illustration, while under tension contacts roll surface 24, which is, as noted before, at a temperature at least as high as the melt temperature of the yarn. As the top portion of yarn 10 contacts heated surface 24, it melts and adheres to the surface. Then, as the yarn starts to break contact with the roll surface it tends to continue toadhere until contact is completely broken thus raising fibrils on the yarn surface. The fibrils are then air cooled thus caus- -mg them to freeze thereby forming permanent fibrils.

Heated roll surface temperature may vary in accordance with many factors, among which are yarn speed and the thermoplastic material from which the yarn is made. However, to achieve proper yarn fibrillation the roll temperature must be, at least, as high as the yarn melting point, but the temperature can be higher if the contact time with the heated roll is proportionally smaller.

As yarn comes into contact with, adheres, and is pulled away from the heated roll surface, fibrils are raised. This action occurs at a particular circumferential portion of the yarn surface. To produce fibrils around the circumference of the yarn, it must be repeatedly passed into and out of contact with the heated roll surface at different points of yarn-roll contact for each pass, i.e., the yarn must be rotated about its own axis. The string-up shown in FIG. 1 effectively achieves this end. That is, as the yarn passes around separator roll 3t) it is rotated about its own axis. Therefore, for example, in four yarn wraps the yarn will be fibrillated at four yarn-roll contact points which are displaced from one another about the yarn circumference. Three or four passes, i.e., wraps, generally fibrillate the yarn quite satisfactorily. Of course, fibrillation can be achieved with only one pass, but the improvement in the yarn is not as marked as when a plurality of passes are made.

FIGURE 4, in general, illustrates yarn fibrillated according to the invention embodiment shown in FIGS. 1, 2, and .3.

Heated roll surface 24 can be made of various materials. However, it is necessary that the surface be wettable by molten synthetic thenmoplastics. Steel, copper, brass, and other like metals are quite adequate for this purpose.

It must be understood that the embodiment shown in the drawing is illustrative only. It would be possible for one skilled in the art to string up the yarn in many other ways to perform the invention.

The process of the invention provides an advantageous method for producing a yarn having improved cover and hand and decreased luster.

It must be understood that even though the invention has been described by reference to a specific embodiment, it is to be broadly construed and limited only by the scope of the app-ended claims.

What is claimed is:

1. A method for forming fibrils on the surface of synthetic thermoplastic yarn comprising:

(a) providing a yarn source;

(b) passing said yarn while under tension into and out of contact with the periphery of a molten-thermoplastic-wettable heated roll, said periphery being heated at a temperature at least as high as the melt temperature of said yarn thus melting the surface of said yarn thereby causing said yarn to temporarily adhere to said roll thus producing fibrils on the surface of said yarn;

(c) cooling said melted yarn surface to below its meltpoint thereby solidifying said fibrils; and

(d) collecting said yarn in an orderly manner.

2. The method of claim 1 wherein the synthetic thermoplastic yarn is made of nylon.

3. The method of claim 1 wherein the synthetic thermoplastic yarn is made of nylon-66.

4. A method for forming fibrils on the surface of synthetic thermoplastic yarn comprising:

(a) providing a yarn source;

(b) passing said yarn while under tension into and out of contact with the periphery of a molten-thermoplastic-wettable heated roll, said periphery being heated at a temperature at least as high as the melt temperature of said yarn thus melting the surface of said yarn thereby causing said yarn to temporarily adhere to said roll thus producing fibrils on the surface of said yarn;

(c) cooling said melted yarn surface to below its melt point thereby solidifying said fibrils;

(d) rotating said yarn about its axis;

(e) repeating the procedure of step (-b);

(f) repeating the procedure of step (d); and

(g) collecting said yarn in an orderly manner.

5. The method of claim 1 wherein the yarn surface is passed into and out of contact with the heated roll periphery at least three times wherein the yarn-roll contact points are displaced from one another about the yarn circumference.

6. The method of claim 4 wherein the synthetic thermoplastic yarn is made of nylon.

7. The method of claim 4 wherein the synthetic thermoplastic yarn is made of nylon-66.

References Cited UNITED STATES PATENTS 1,962,683 6/1934 Dreyfus 264-484 2,371,075 3/1945 Spertus 264l64 2,380,363 7/1945 Land et al 264-2 X 2,385,358 9/1945 Hanson 264-l64 X 3,096,563 7/1963 Messinger -2 262 X 3,141,051 2/1964 Takai 264-293 X ALEXANDER H. BRODMERKEL, Primary Examiner.

J. H. WOO, Assistant Examiner. 

